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add “set -o arc4random”, RTFM for details

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This commit is contained in:
tg
2007-08-12 13:42:23 +00:00
parent cf2eb697e2
commit 499327f7b8
9 changed files with 140 additions and 61 deletions
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108
var.c
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@@ -2,7 +2,7 @@
#include "sh.h"
__RCSID("$MirOS: src/bin/mksh/var.c,v 1.42 2007/07/22 14:01:50 tg Exp $");
__RCSID("$MirOS: src/bin/mksh/var.c,v 1.43 2007/08/12 13:42:23 tg Exp $");
/*
* Variables
@@ -23,6 +23,8 @@ static void getspec(struct tbl *);
static void setspec(struct tbl *);
static void unsetspec(struct tbl *);
static struct tbl *arraysearch(struct tbl *, int);
static int rnd_get(void);
static void rnd_set(long);
/*
* create a new block for function calls and simple commands
@@ -849,25 +851,96 @@ makenv(void)
}
/*
* Someone has set the srand() value, therefore from now on
* we return values from rand() instead of arc4random()
* Get us a random number, either from rand(3) or arc4random(3), with
* the latter being preferred. If Flag(FARC4RANDOM) is 0, we use rand(3),
* otherwise arc4random(3). We have static caches to make change_random
* and writes to $RANDOM a cheap operation.
*/
#if HAVE_ARC4RANDOM
static int use_rand = 0;
static uint64_t rnd_cache = 0;
static char rnd_lastflag = 2;
#endif
static int
rnd_get(void)
{
#if HAVE_ARC4RANDOM
#if HAVE_ARC4RANDOM_PUSHB
uint32_t rv = 0;
#endif
if (Flag(FARC4RANDOM) != rnd_lastflag) {
if (Flag(FARC4RANDOM) == 0) {
/* transition to 0 by set: srand */
srand(arc4random() & 0x7FFF);
} else if (rnd_lastflag == 0) {
/* transition from 0: addrandom */
rnd_cache ^= rand();
}
rnd_lastflag = Flag(FARC4RANDOM);
}
if (Flag(FARC4RANDOM)) {
if (rnd_cache)
#if HAVE_ARC4RANDOM_PUSHB
rv = arc4random_pushb(&rnd_cache, sizeof (rnd_cache));
#else
arc4random_addrandom(&rnd_cache, sizeof (rnd_cache));
#endif
rnd_cache = 0;
return ((
#if HAVE_ARC4RANDOM_PUSHB
rv ? rv :
#endif
arc4random()) & 0x7FFF);
}
#endif
return (rand() & 0x7FFF);
}
static void
rnd_set(long newval)
{
#if HAVE_ARC4RANDOM
rnd_cache ^= (((uint64_t)newval) << 15) | rand();
if (Flag(FARC4RANDOM) == 1)
return;
if (Flag(FARC4RANDOM) == 2)
Flag(FARC4RANDOM) = 0;
/* transition to 0 by write: only srand */
rnd_lastflag = 0;
#endif
srand(newval & 0x7FFF);
}
/*
* Called after a fork in parent to bump the random number generator.
* Done to ensure children will not get the same random number sequence
* if the parent doesn't use $RANDOM.
*/
void
change_random(void)
change_random(uint64_t newval)
{
int rval = 0;
newval &= 0x00001FFFFFFFFFFF;
newval |= (uint64_t)rand() << 45;
#if HAVE_ARC4RANDOM
if (use_rand)
if (Flag(FARC4RANDOM)) {
rnd_cache ^= newval;
return;
}
#endif
rand();
rval += newval & 0x7FFF;
newval >>= 15;
rval += newval & 0x7FFF;
newval >>= 15;
rval += newval & 0x7FFF;
newval >>= 15;
rval += newval;
rval = (rval & 0x7FFF) ^ (rval >> 15);
srand(rval);
}
/*
@@ -918,12 +991,7 @@ getspec(struct tbl *vp)
break;
case V_RANDOM:
vp->flag &= ~SPECIAL;
#if HAVE_ARC4RANDOM
if (!use_rand)
setint(vp, arc4random() & 0x7FFF);
else
#endif
setint(vp, rand() & 0x7FFF);
setint(vp, rnd_get());
vp->flag |= SPECIAL;
break;
case V_HISTSIZE:
@@ -963,7 +1031,7 @@ setspec(struct tbl *vp)
break;
case V_OPTIND:
vp->flag &= ~SPECIAL;
getopts_reset((int) intval(vp));
getopts_reset((int)intval(vp));
vp->flag |= SPECIAL;
break;
case V_TMPDIR:
@@ -985,7 +1053,7 @@ setspec(struct tbl *vp)
break;
case V_HISTSIZE:
vp->flag &= ~SPECIAL;
sethistsize((int) intval(vp));
sethistsize((int)intval(vp));
vp->flag |= SPECIAL;
break;
#if HAVE_PERSISTENT_HISTORY
@@ -999,13 +1067,7 @@ setspec(struct tbl *vp)
break;
case V_RANDOM:
vp->flag &= ~SPECIAL;
srand((unsigned int)intval(vp));
#if HAVE_ARC4RANDOM
use_rand = 1;
#if HAVE_ARC4RANDOM_PUSH
arc4random_push((unsigned)vp ^ (unsigned)rand());
#endif
#endif
rnd_set(intval(vp));
vp->flag |= SPECIAL;
break;
case V_SECONDS:
@@ -1026,7 +1088,7 @@ setspec(struct tbl *vp)
case V_LINENO:
vp->flag &= ~SPECIAL;
/* The -1 is because line numbering starts at 1. */
user_lineno = (unsigned int) intval(vp) - current_lineno - 1;
user_lineno = (unsigned int)intval(vp) - current_lineno - 1;
vp->flag |= SPECIAL;
break;
}